The invention relates to a portable apparatus for machining pipe ends, comprising a base plate for putting the apparatus on any desired base, an accommodating housing which is connected to the base plate and is intended for accommodating a drive arrangement and a gearing arrangement for driving a cutting tool and for accommodating a feed arrangement for feeding the cutting tool in the direction of a pipe end to be machined, a clamping device for clamping a pipe to be machined, a coupling arrangement for coupling the apparatus to a drive source, and a feed control device for controlling the feed of the cutting tool.
In pipeline construction, the end faces of the pipe ends to be connected must be reworked perpendicular to the pipeline axis as a preparatory step before the assembly of the pipeline sections and fittings by welding processes. In particular thin-walled pipes, that is to say those with wall thicknesses of less than 3 mm, are butt-welded and therefore have to be faced, that is to say made exactly at right angles to the pipeline axis. This preparatory work is necessary in order to remove any possible chips or unevenness, present after the cutting-off or sawing operation at the pipe end, before the welding operation.
An apparatus of the generic type for machining pipes or cylindrical workpieces has been disclosed by U.S. Pat. No. 5,941,145. A drive shaft and a feed control for controlling a tool carrier are arranged in an accommodating housing which has been split in two in the region of the gearing arrangement. The housing is fastened to a base plate. Located in front of the housing is a clamping device. The pipe or the cylindrical workpiece to be machined is clamped in the clamping device by the screwing movement of a spindle as in a machine vice.
The foregoing object is achieved by a portable apparatus for machining pipe ends, comprising a base plate for putting the apparatus on any desired base, an accommodating housing which is connected to the base plate and is intended for accommodating a drive arrangement and a gearing arrangement for driving a cutting tool and for accommodating a feed arrangement for feeding the cutting tool in the direction of a pipe end to be machined, a clamping device for clamping a pipe to be machined, a coupling arrangement for coupling the apparatus to a drive source, and a feed control device for controlling the feed of the cutting tool, a clamping lever being arranged such that it can be fastened in the clamping device so as to be movable from a first unclamped position into a second clamped position, and the clamping lever having an eccentric contour.
It is advantageous that the pipe to be machined can be clamped both quickly and reliably. This is achieved by the clamping device being essentially composed of a one-piece annular retaining ring which is arranged so as to be firmly connected to the accommodating housing, a curved and movable retaining element being arranged inside the retaining ring, this retaining element being arranged so as to be movable by the clamping lever with respect to the retaining ring in the circular space enclosed by the retaining ring. This is also achieved by two semicircular half shells for clamping the pipe to be machined being arranged in such a way that they can be detachably fastened in the circular space enclosed by the retaining ring. Furthermore, the clamping is simplified by the two half shells being designed to be identical and interchangeable.
It is also advantageous that the working step for clamping the pipe can easily be automated. This is achieved by the of clamping lever being arranged in the retaining ring in such a way that it can be fastened in a movable manner by means of an eccentric pin. This is also achieved by the clamping lever having a clamping surface with an eccentric contour which is designed in such a way that, during the rotating clamping movement of the clamping lever about the eccentric pin, the retaining element can be moved towards the half shells.
Furthermore, it is advantageous that, by means of the clamping lever, the pipe, with a simple movement in one direction, can be both positioned and clamped in the apparatus for machining the pipe end. This is achieved by the clamping lever having a clamping surface with an eccentric contour which is designed in such a way that, during the rotating clamping movement of the clamping lever about the eccentric pin, the half shells are moved towards one another. This is also achieved by the eccentric contour being composed of two sectional contours, arranged so as to adjoin one another and being of different design, in such a way that a first sectional contour, during the rotating clamping movement of the clamping lever about the eccentric pin within a first rotary-angle range of about 90xc2x0, moves the half shells towards one another by a first displacement distance S and that a second sectional contour, during the rotating clamping movement of the clamping lever about the eccentric pin within a second rotary-angle range of about 120xc2x0, moves the half shells towards one another by a second displacement distance S/2.
Furthermore, it is also advantageous that the feed of the cutting tool can be judged in a simple and accurate manner by the operating personnel. This is achieved by a digital display for displaying the tool feed being arranged such that it can be connected to the feed control device.